FACTORS DETERMINING THE DISTRIBUTION OF COEXISTING ...

POLISH JOURNAL OF ECOLOGY 

(Pol. J. Ecol.) 

54 3 379–386 2006 

Short research contribution 

Botond BAKÓ 1 , Kristóf HECKER 2 

1 

Office of Nature Conservation, Költő u. 21, H-1121, Budapest, Hungary 

2 

Department of Zoology and Ecology, Szent István University, Páter Károly u. 1., H-2103, Gödöllő, 

Hungary, e-mail: hecker.kristof@mkk.szie.hu 

FACTORS DETERMINING THE DISTRIBUTION 

OF COEXISTING DORMOUSE SPECIES (GLIRIDAE, RODENTIA) 

ABSTRACT: This study investigated coexistence 

of three dormouse species living in the 

same habitat, Naszály-hill, in the north-eastern 

part of the Danube-bend (47°49’N, 19°08’E). The 

vegetation of the area is very diverse, comprising 

a mosaic of orchards with natural forests and forest 

plantations. Data were collected from 1999 to 

2005 with wooden nest boxes and from 2002 to 

2005 also plastic nest tubes were used. Study area 

was approximately 6 ha. 

All three species (hazel dormouse Muscardinus 

avellanarius L., forest dormouse Dryomys 

nitedula Pall. and fat dormouse Glis glis L.) have 

different ecological requirements. However, they 

occurred simultaneously in some microhabitats 

and in some places one species clearly predominated. 

We also observed how the ongoing succession 

process in the former orchards affected the 

distribution of dormice. 

There were seasonal differences in timing of 

emergence from hibernation, greatly affecting spatial 

distribution of the different species. Hazel dormice 

were first to appear in nest boxes and/or tubes, 

in March, then forest dormice in April and fat dormice 

in June. As numbers of fat dormice increased 

the smaller species withdrew from using the nest 

boxes. Fat dormice reached peak numbers in summer 

and they entered hibernation by October. 

KEY WORDS: dormouse, coexistence, habitat, 

environmental factors, nest box/tube 

The coexistence of several dormouse 

species in one locality with different habitat 

types offers a unique possibility to study 

habitat preference of the species. 

Our research site, the Naszály-hill, has 

been known as a habitat of all three dormouse 

species that occur in Hungary (Bakó 

and Gál 1999, Gál 1999). Our first studies 

began in 1995 using live-traps. Based on the 

early results we started an improved research 

project in 1999. The aim of our study was to 

find out, which environmental factors enable 

the coexistence of different dormouse species 

in one area and to observe how the adjacent 

vegetation types and the ongoing succession 

process affect the spatial distribution of the 

coexisting dormouse species. Research topics 

also included the seasonal and yearly differences 

in the appearance and occupancy of 

nest boxes/tubes by the dormice. 

The study area (in total ca. 6 ha), 

Naszály-hill (652 m a.s.l.), lies near the 

city of Vác in the north-eastern part of the 

Danube Bend (47°49’N, 19°08’E). Mainly 

dachstein limestone, with dolomite in some 

places, dominates in the bedrock and contains 

nine caves of different size. The vegetation 

is extraordinarily diverse as it lies 

on the ranges of the distribution area of 

journal 7.indb 379 2006-09-23 11:28:41

380 Botond Bakó, Kristóf Hecker 

Fig. 1. Site map of the location showing the woody vegetation patches. 

Legend to the numbers of patches see in Table 1. 

Table 1. Main and other abundant tree and shrub species in the different vegetation types and the size 

of the plots where dormice were surveyed. 

No. Vegetation type Main species Other abundant species 

Size 

of plot 

No. of boxes 

1999/2002/ 

2005 

1. 

Hedge around 

abandoned orchard 

dogwood (Cornus 

sanguinea L.), plum 

(Prunus domestica L.) 

dogrose (Rosa canina L.), 

cherry (Cerasus avium /L./ 

Moench), privet (Ligustrum 

vulgare L.) 

0.6 ha 70/50/50 

2. Shrub dogwood dogrose, cherry, privet 0.5 ha –/50/50 

3. Young pine stand 

Austrian pine (Pinus 

nigra Link) 

privet 0.3 ha –/50/50 

4. Abandoned orchard plum 

dogwood, common lilac 

(Syringa vulgaris L.) 

0.6 ha 35/35/38 

5. Mixed pine forest 

Scots pine (Pinus sylvestris 

L.) 

ash (Fraxinus excelsior L.) 

0.6 ha –/12/35 

6. 

Edge of oak-hornbeam 

forest 

sessile oak (Quercus 

petraea /Matt./ Liebl.) 

hedge maple (Acer campestre 

L.), ash 

0.7 ha 35/21/35 

7. 

Oak-hornbeam 

forest 

sessile oak 

hornbeam (Carpinus betulus 

L.), hedge maple 

0.6 ha –/50/50 

8. Turkey oak forest 

turkey oak (Quercus 

cerris L.) 

white oak (Quercus pubescens 

Willd.), ash 

0.7 ha –/–/70 

journal 7.indb 380 2006-09-23 11:28:41

Distribution of coexisting dormouse species 

381 

different flora units (Füri and Sinkóné 

Póka 1996). Natural and planted vegetation 

plots also change in space and time. 

Beside the different types of grassland there 

are planted hedges and orchards, with different 

fruit trees (mostly apple, plum and 

pear). Most of the orchards have been out 

of cultivation for decades, but some are 

still in use. The mixed oak forests (Quercus 

petraea (Matt.) Liebl., Quercus cerris L., 

Quercus pubescens Willd.) both with dense 

and sparse underbrush, and planted pine 

forest (Pinus sylvestris L. and Pinus nigra 

Link) of different age occur in the area. 

The older pine forests are already mixed 

with ash (Fraxinus excelsior L.), some areas 

are monocultures of young pines. On the 

top of the hill a beech (Fagus sylvatica L.) 

forest (Gál 1999) occurs. 

Populations of the three dormouse 

species: hazel dormouse Muscardinus avellanarius, 

fat dormouse Glis glis and forest dormouse 

Dryomys nitedula occur in the study 

area (Bakó and Gál 1999, Gál 1999). 

From 1999 to 2005 nest boxes were 

used to collect data. They were placed along 

a transect across different vegetation types 

like an abandoned orchard, a hedgerow and 

the edge of a deciduous forest dominated by 

sessile oak (Quercus petraea) (Bakó et al. 

2002). 

The first 150 wooden bird nest boxes 

(height 30 cm, width 15 cm and depth 15 cm) 

were set up for dormice in autumn 1999, 

they were followed by 150 plastic nest tubes 

(height 10 cm, width 10 cm and depth 

30 cm) in summer 2002 (Bakó et al. 2002). 

In spring 2005 additionally 70 new wooden 

dormouse nest boxes (20 × 20 × 20 cm) and 

35 new plastic nest tubes were introduced. 

The boxes were fixed at 1.5–2.5 m above the 

ground, 5 m apart, the wooden ones faced 

the tree trunk, the plastic tubes were on 

horizontal branches. This height was found 

to be suitable for dormice and easy to check 

(Morris 2004). With this nest box density 

the availability of nesting places is not a limiting 

factor (Bright et al. 1994, Juškaitis 

2003, 2006). 

First observations suggested that a nest 

tube made mainly of smooth plastic was not 

fully suitable, although several nestings were 

recorded. So we roughened the inner surfaces 

with sand. Some nest boxes were lost 

for various reasons, but with the new ones we 

managed to complete the data series. 

Eight vegetation types were surveyed 

with nest box system (Table 1), and their location 

can be seen in Fig. 1. 

We checked the nest boxes and nest tubes 

monthly and cleaned them only in winter. 

We collected data on animals found: after 

sexing the animals were weighed, body and 

tail length and the length of the left ear and 

left hind foot were measured. Empty nests 

were also recorded, but only the new nests 

were included in the data processing. 

The total occupation in the wooden 

boxes and plastic nest tubes (Figs 2 and 3) is 

a sum of the records on dormice, observed 

new nests, food remains, faeces and other 

signs of activity. There were differences in 

the use of the two different nest box types, 

so in spring 2005 we started a comprehensive 

investigation to find out how this difference 

influenced the results (Fig. 4). Muscardinus 

was the only dormouse species 

successfully breeding in plastic tubes, Glis 

and Dryomys were found only few times. 

There were 16 nest boxes and tubes (5.7%), 

which were never used (no nest or any sign 

of occupation) mainly in the area of the 

planted young pine stand (5 plastic tubes) 

and the oak forest (8 plastic tubes) with 

sparse underbrush. 

In the years 2000–2005 we had a total of 

341 records on dormice. The percentage of 

species can be seen in Fig. 5. 

Although not all vegetation plots are adjacent 

to each other, there are no geographical 

barriers or habitat corridor gaps between 

them. So, theoretically all surveyed plots can 

be reached by the animals. Moreover, there 

are neighbouring vegetation types, which 

have different plant species composition. 

Muscardinus was the only dormouse species 

found in every plot, and the only species 

in the young pine stand and the shrub (Fig. 6). 

We got less records from the hedge in the 

last three years, but at the same time the 

number of hazel dormice in the neighbouring 

pine stand and shrub increased. In the 

plots where Glis was very abundant (orchard, 

edge of oak-hornbeam forest, turkey oak forest), 

only few records of Muscardinus were 

obtained. 

journal 7.indb 381 2006-09-23 11:28:41


Fig. 2. Changing in the occupancy by dormice (%) of the wooden nest boxes by dormice during the 

whole study period (2000–2005). 

Fig. 3. Changing in the occupancy by dormice (%) of the plastic nest tubes during the study period 

(2002–2005). 

Glis was absent from the shrub habitat 

and the young pine stand, as was Dryomys 

(Fig. 6). Dryomys was also absent from the 

edge of oak-hornbeam forest. Glis occurred 

in higher numbers in the hedge, orchard, edge 

of oak-hornbeam forest and in the turkey oak 

forest, while most data on Dryomys were collected 

in the abandoned orchard (Fig. 6). 

All three species occurred in five out of 

eight plots: hedge, orchard, mixed pine forest, 

oak-hornbeam forest and turkey oak forest, 

although in the oak-hornbeam forest, we 

found only a single Glis and Dryomys. 

The results on seasonal distribution 

showed (Fig. 7) that dormice used the nest 

boxes to a different extent. Muscardinus used 

nest boxes/tubes during the whole active season, 

Dryomys numbers peaked in May and 

some specimens could be found in August. 

Glis was found mostly in late summer and 

autumn, when they appeared to play a very 

dominant role. 

journal 7.indb 382 2006-09-23 11:28:41


383 

Fig. 4. Proportion of monitored animals, nests 

and other signs of activity in the turkey oak forest 

in the two different nest box types (per 100 nest 

box checks). 

Fig. 5. Percentage of the dormouse species in the 

total number of caught dormice. 

Fig. 6. Proportion of three 

dormouse species caught 

in the different vegetation 

types (per 100 nest box 

checks) 

Legend: 

1. hedge, 

2. shrub, 

3. young pine stand, 

4. abandoned orchard, 

5. mixed pine forest, 

6. edge of oak-hornbeam 

forest, 

7. oak-hornbeam forest, 

8. turkey oak forest 

* boxes placed in 2002, 

** boxes placed in 2005 

journal 7.indb 383 2006-09-23 11:28:41


Fig. 7. The average number of dormouse individuals in all boxes in the different months of the whole 

survey period (2000–2005). 

Other species nesting in the boxes were 

Apodemus flavicollis Melchior, Apodemus 

sylvaticus L., Parus major L., Parus caeruleus 

L., Jynx torquilla L., Vespa crabro L. and Bombus 

terrestris L. 

The number of records on dormice collected 

during our survey confirms that the 

use of nest boxes/tubes for surveys provided 

a good source of data (Robel and Leitenbacher 

1993, S chlund et al. 1993, Morris 

1997, S orace et al. 1998, 1999, Juškaitis 

1995, 1999, 2000, Koppmann-Rumpf et 

al. 2003, Bakó et al. 2002). There was difference 

in the use of wooden boxes and plastic 

nest tubes. The preliminary results of the 

comprehensive investigation let us suppose 

that fat dormice avoid the plastic nest tubes, 

forest dormice seem to make no difference, 

whereas hazel dormice nested mainly in the 

plastic tubes. In an earlier study we found 

out that Muscardinus made no difference 

between the two types of nest boxes, but 

Dryomys and Glis had a clear preference to 

wooden boxes (Hecker and Bakó 2005). 

These observations show that records gained 

using wooden nest boxes are more reliable 

for all three species. We think this is because 

the inner hole is bigger in the wooden nest 

boxes and more suitable for Glis, but even for 

Dryomys, because the only two forest dormice 

found in the nest tubes in 2005 were juveniles. 

We think that Muscardinus used the 

tubes more because of the competition with 

the other dormouse species. However the 

wooden boxes are heavier and it is hard to 

fix them on shrubs. Probably the size is more 

important than the material, so it would be 

useful to test larger plastic nest boxes e.g. of 

the size of wooden nest boxes. 

The species composition changed in 

2005. Before that year hazel dormouse was 

the most abundant similarly to nationwide 

trends (Hecker et al. 2003). In 2005, 139 

records were obtained on Glis, which made 

41% of all dormouse records during whole 

study period. Observed increase in Glis numbers 

might have been caused by the change in 

acorn production, as it was observed in other 

studies (S chlund et al. 2002). However, we 

did not monitor acorn production to support 

this statement, but a lot of the nest boxes and 

plastic nest tubes were filled up with acorn 

shells much more than in previous years. 

The differences in distribution of dormouse 

species cannot be explained only by 

spatial factors. All but one of the plots were 

adjacent to one or more plots, and all were 

linked together by forest patches or habitat 

corridors. The largest difference in species 

composition was found between the hedge, 

journal 7.indb 384 2006-09-23 11:28:42


385 

with all three dormouse species present, 

and the neighbouring shrub and young pine 

stand, only with Muscardinus. 

Those habitats where all three dormouse 

species occurred contained various tree 

and shrub species, providing food (fruits or 

seeds) at different times. By contrast, in the 

shrub where dogwood (Cornus sanguinea L.) 

dominated or in the young pine stand only 

few shrub species provided source of food. 

Dryomys was the only species, which was 

not found at the edge of oak-hornbeam forest. 

It agrees with the results of the former 

survey (Gál 1999). However, in the neighbouring 

oak- hornbeam forest one Dryomys 

was recorded in 2005. 

There are certain microhabitats where 

mainly or only hazel dormice appear: young 

pine stand, shrub, oak-hornbeam forest. The 

changes of the spatial distribution found 

during the five years of our survey suggest 

that the increase of Glis forced back Muscardinus 

to the habitats with less species-rich 

structures. In the last three years of the study 

(2002–2005) we observed a decrease in the 

records on Muscardinus in the hedge but at 

the same time the numbers in the adjacent 

shrub and young pine stand increased. 

In the last years vegetation succession 

was very intensive, because the orchards 

were taken out of cultivation. The shrub vegetation 

(Viburnum L., Prunus L. and Euonymus 

L. species) has got thicker and formed a 

more continuous habitat. This is a possible 

reason why more fat dormice appeared in 

the hedgerow and numbers of Dryomys increased 

in the abandoned orchard. 

Data on seasonal distribution show that 

nest boxes were used in the whole active season, 

but to different extent. The decrease in 

using of nest boxes by Muscardinus and Dryomys 

in July–August might be due to the late 

re-appearance of Glis after hibernation. Glis 

probably forced out the smaller dormouse 

species. In some cases we found gnawed skin 

of young Dryomys and Muscardinus specimens 

in Glis nests, which confirms the strong 

competition between the species. To answer 

these questions we started a field survey in 

a location where only Dryomys and Muscardinus 

occur. 

Our results showed that coexistence of 

different dormouse species was possible in 

the same habitats – even in nest boxes next to 

each other. In our study site we found noticeable 

differences between the influence of the 

vegetation types and structures, but a more 

detailed field survey is needed to explore interspecies 

behaviour patterns. 

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(Received after revising June 2006) 

journal 7.indb 386 2006-09-23 11:28:42

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